Trailing wire antenna



2 Sheets-Sheet 1 R. O. ROBINSON, JR

TRAILING WIRE ANTENNA umm WI July 25, 1961 Filed Aug. 1. 1952 July 25, 1961 R. o. ROBINSON, JR 2,993,443

TRAILING WIRE ANTENNA Filed Aug. 1. 1952 2 Sheets-Sheet 2 nited States Patent licei This invention relates to antenna systems for use with projectiles. The oscillator acts both as a transmitter means Which has the effect of substantially increasing the electrical lengthof a projectile, thereby making possible a projectile fuze having certain 4advantages over existing fuzes.l

One of the most reliable devices for detonating -anex# plosiveprojectile in the proximity of a target is the radio proximity fuze; In its basic form, this fuze consistsY of a proximity sensitive radio frequency oscillator and associated amplifiers, and a ring circuit, all Abuilt into 'the projectile. The oscillator acts both as a transmitter and receiver and is coupled to the projectile casing in such a manner as to cause the latter to act as a radiator.

When the transmitter is operating, that is, after the pro` jectile has been fired, a radio frequency signal provided by the oscillator is emitted from the projectile. A target reflects-parts of this signal back to the projectile where itreacts upon the oscillator. If the reflected waves are out' of phase with the transmittedwaves, the oscillatorA load is increased, thereby increasing the current in the oscillators pl-ate circuit; while if the reected waves are in phase, the oscillator load is decreased thereby decreasing the current in the oscillators plate circuit. The oscillatory plate current generated in this m-anner produces a pulse which, when amplified, is utilized to actu-ate the ring circuit ofthe projectile. j

The characteristics of the radiating system are an irnportant part of this arrangement inasmuch as they determine the range of suitable operating frequencies and the sensitivity' of the fuze. Various antenna constructions have been employed in the past. The invention operates in conjunction with a conventional nose excited type of projectile in which oscillatory currents are caused4 toow over the entire surface of the projectile body.

It is the primary object of this invention to provide a means for substantially increasing `the effective electrical length of the projectile and thusprovide Ibetter radiation resistance and pattern characteristics than were previouslyv obtainable. Y i

It is a further object of the invention to provide` a radiatingsystem for la projectile. that permits a -greater spread-ofoperating frequency for the projectile fuze, therebyjreducing the success of enemy counter-measures inprematurely detonating or jamming the fuze. In the case of proximity fuzed projectiles being used against ground targets, `an additional advantage realized by increasing the spread of operating frequency is that the use of a low RF frequency reduces the 'number` of cycles of the 'signalYpccugjringmduringnthe time the fuzeican lire, thereby reducingvthe dispersion of Iburst height-in fuzes. That is', the number of reflected signal waves of sufficient intensity to actuate the fuze are reduced, for limiting the range over which the fuze will be fired.

The invention also has for an object the provision of means by which greater fuze sensitivity may be achieved, with the result that the distance from the target at which a projectile will detonate may be increased. This is also of'particular importance in the Vapplication of proximity fuzes to the smaller projectiles.

Another important object of the invention is to provide a radiating system by means of which standardization of fuze operating frequency and sensitivity may be iatenfed .hay 25, 1961 i 2 achieved. 'Ihis standardization is made possible by substantially increasing the effective electrical length of the shorter projectiles so that all projectiles have the same electrical length.

Briefly, these and other objects .are 4achieved by providing a trailing wire electrically connected to the b-ase of a projectile which has conventional nose excitation, and means adjacentthe projectile base for packaging the wire so that it will be automatically projected from the rear of the projectile upon firing of the latter.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description vwhen considered in connection with the accompanying drawings wherein:

FIG. 1 is a diagrammatic view showing trailing wires applied to projectiles of different sizes;

FIG.` 2 is an enlarged view showing in section some of the components of a proximity fuze in the nose of a projectile, the projectileitself being shown in side eleva- FIG. 3 is an' enlarged partial cross section through the base of a proximity fuzed projectile, showing the trailing Wire packaged in the projectile base;

. FIG; 4 is a view similar to that of FIG. 3, but showing the trailing wire released; and

FIG. 5 is a sectional view on the line 5-5 of FIG. 3.

Referring to FIG. 2, the invention is shown applied to a conventional projectile 10. 'I'he projectile 10 has -a casing 12 and a rotating band v14. I'Ilhe projectile car- -ries the usual explosive charge, indicated at 16 in FIGS. 3 and v4. A proximity fuze, generally similar to the one disclosed-in co-pending application, Serial No. 471,388, filed January 6, 1943, M. A. Tuve et al., inventors, is carried in the nose of the project-ile; however, only so much of the fuze is shown in FIG. 2 as is necessary for an understanding of the present invention. jectile is shown as having a plastic nose piece 1S Which :is ttedto' a cylindrical housing 20 which is itself carin a second cylindrical housing 22 threaded into a bore provided in the projectile casing 1i). Shield cans 24 and 26, which .house the oscillator components and the amplifier components, respectively, of the fuze circuit,.

are tted, together with the other components not shown, into the plastic nose piece 18 and the cylindrical housing members 20 and 22. i

' The vacuum tube employed in the oscillator circuit of the uze is shown at 28 as being positioned centrally of the shield can 24. A tube 33 of insulating material, which serves 'asthe form on which the tank coil 32 of the oscillator circuit is wound, is tted -around the vacuum tube 2S. lThese circuit elements, and others not shown, are held in place in shield' can 24 by means of a potting compound 34. One terminal of the coil 32 is connected to the nose cap exciterIk 36 fitted in the nose Vpiece 18, while the other terminal of the coil is connected to common at the bottom of the shield can 24.

A trailing wire 40, electrically connected to the projectile'casing v10 and 'the/tank coil 32, is carried at the base end' ofthe projectile; The wire 40 may itself be a bare or an insulated conductor. As can be seen in FIGS. 3 and 4, a threaded bore is provided in the projectile base to receive a cylindrical housing 42 sealed in place by a lead seal 44. The housing 42 has an end plate 46 which is releasably held on the housing by two or more spring pressed detents 48 carried in apertures in the housing. While the projectile is stationary the detents 48 are urged into apertures in the platel 46 by the springs 50. However, when the projectile isfred, the centrifugal force developed by its rotation urges the detents outwardly thereby freeing the plate. A compressed spring 52 held in position in the housing 42 by the circular ridge 54 formed on the inner surface of the housing bears on the plate 46 to force the latter free of the housing 42.

The wire 40 is coiled in the housing by a well known technique involving imparting a twist to the individual turns of wire so that the Wire uncoils when released. The Wire is fastened at one end to an eye 56 provided in the housing. As can best be seen in FIG. 5, a slot 58 is provided in the ridge 54 so that the last turn of the Wire can be led to the eye 56 and fastened without beingk kinked over the ridge. At its free end the wire carries a drag ball 60 which assists in uncoiling-the wire 40 and holding it in its trailing position. A recess 62 and a channel 64 leading to the recess are provided in the plate 46 to accommodate the drag ball and the adjacent partial turn of the antenna wire.

While the manner in which the wire 40 isr fed from the housing 42 into a trailing position behind the projectile is for the most part apparent, a brief explanation of this aspect of the operation of the invention follows. Referring again to FIG. 3', the wire 40' is shown packaged in the housing 42 and held in that position by the plate 46. Upon the projectiles being fired, the detents 48 are moved outwardly by the centrifugal force developed by rotation of the projectile; however, the plate 46 remains in the position shown in FIG. 3, because the pressures developed at firing actV on the plate as long as the projectile is in the barrel. After the projectile is freed, the spring 52 expels the plate 46, and the wire begins to uncoil as shown in FIG. 4. Friction on the drag ball 60, and the twist imparted to wire 40 by the coiling technique, cooperate toextend the wire into trailing position along the axis of the projectile as shown in FIG. l.

The manner in which the trailing wire 40 serves to increase the effective electrical length of the projectile, thus enabling standardization of fuzes, can be seen by reference to FIGS. l and 2. The wire 40 is electrically connected to one terminal of the oscillator tank coil through the shield cans 24 iandv 26, theprojectile casing 10, and eye 56. With this arrangement, the nose cap exciter 36 will excite the projectile casing 10 and the Wire 40 so that Vthe casingand the wire form the main part of the radiating system. In FIG. 1,. projectiles Y10 and a of dilerent sizes are shown provided'with wires 40 and 40a of different lengths so that the effective elect-rical lengths of the combined projectiles and trailing pressed detents have been disclosed to retain the wire in coiled position, a` solder or plastic meansV which could be meltedpr burned could be employed to perform that function.

Obviously many other modiiications and variationsv of' the present invention are 4possible in the light of the above teachings. It is therefore to be-understood that within 4 l the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is: 1. In ya projectile having a proximity fuze, said projectile having a base, the combination comprising a housing carried in the base, a coiled wire in.` said housing,

said coiled wire having a twist imparted thereto wherebythe wire tends to uncoil when released, one end of saidl wire being electrically connected to said housing, drag means carried on the other end of said Wire, means for retaining said wire in coiled position in the housing, said means including a plate releasably Iheld in the housing lso that upon removal of said plate said Wirev will extend from the projectile, and means operable by centrifugal force for releasing said plate.

2. In a projectile having a nose proximity fuze, saidr projectile having a base, said fuze includingan oscillator circuit having a tank coil, said tank coil being electrically connected to the nose of said projectile, the combination comprising ahousing carried in the base, a coiledl Wire in said housing, one end of said Wire being electrically connected to ysaid housing, and means for releasably retaining said wire in coiled position in the housing sothat upon removal of said retaining means said wire will extend from the projectile.

3. In a projectile having a proximity fuze, said projectile having a base, said fuze including an oscillator,

circuit having a tank coil, a housing carried in the base;

Y said tank coil being electrically connected by means of the projectile body to said housing, a coiled wire in said housing, one end of said wire being electrically connected to said housing, means for releasably retaining ysaid wire in coiled position in the housing, and means -for'expelling said wire from said housing into trailing position atthe rear of'said projectile.

4. In a projectile having a proximity fuze, said profor coupling the electromagnetic energy generated by said oscillator to said casing whereby the latter is caused to radiate said enengy, and an extensible conductor con- Y nected to said projectile casing, said extensible conductor being adapted to be carried in trailing relationship-atthe Y teriaLsaid proximity fuze including an oscillator having` rear of said projectile, therebyV increasing the eiectiv electrical length of said projectile.

5. In a projectile having a proximity fuze, said projec-J tile includingY a casing of electric current conducting maa tuned circuit, means connected to said tuned circuit for coupling the electromagnetic energy generated by'said oscillator to said casing whereby the latter is caused to` radiate said energy, a housing in said projectilecasing,

an extensible conductor carried in said housing-and'elec- Vtrically connected to said projectile casing, and means for ejecting said conductor into trailing position at the rear of said projectile, thereby increasing the effective elecn trical length of said projectile.

References cited in the file of this patent i UNrn-:D STA-res PATENTS A Buckley Jury 1; v193e 2,557,949"k Deloraine. .Tune 26, 1951 f UNITED STATES ITENT OFFICE Patent N00 29934LI3 Ralph Oo RobmoonI Jn@ above numbered patpears in the hould read as It is `hereby certified that error ap d Letters Patent s ent requiring correction and that the sai corrected below.

Iine IOSl for "The oscillator acte both as a vention ,relates to Column L,

d In more detailu the in transmijtter:n rea nge signed and seaIed this 3rd day of April I%2 Attest: ERNEST W. SWIDER DAVID L. LADD Commissioner of Patents Attesting Officer UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent Noo 2U993u443 July 25 1.961

Ralph OQ Robnsong .LIFO

r appears n the abo-ve numbered pat- It is hereby certified that erro etters Patent should read as ent requiring correction and that the said L corrected below.

line lOu for "The oselletoifd aets both as a transmitter read e Signed and sealed this 3rd day of April l92 Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents 

